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DANIEL RUDMAN, MICHAEL H. KUTNER, MARTIN A. GOLDSMITH, JANIS KENNY, HUNTER JENNINGS, RAYMOND P. BAIN, Further Observations on Four Subgroups of Normal Variant Short Stature, The Journal of Clinical Endocrinology & Metabolism, Volume 51, Issue 6, 1 December 1980, Pages 1378–1384, https://doi.org/10.1210/jcem-51-6-1378
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Abstract
In a previous report, we classified normal variant short stature (NVSS) children into four subcategories on the basis of magnitudes of anabolic and linear growth responses to exogenous human GH (0.532 U⁄kg BW¾ -day for 10 days). Subgroup 4 was hyperresponsive to both actions of the hormone; subgroups 1 and 2 showed no linear growth response, and subgroup 1 was resistant to the anabolic effect as well; subgroup 3 was intermediate between groups 2 and 4 in both types of response.
In this study, 21 NVSS children, aged 8-10 yr, who had grown less than 2.6 cm during the previous year were classified on the basis of human GH responses as follows: 6 in subgroup 1, 10 in subgroup 2, 2 in subgroup 3, and 3 in subgroup 4. The mechanisms underlying these subgroups were investigated by measuring nocturnal release of endogenous GH by both RIA and radioreceptor assay (RRA), serum somatomedin C level by RIA, and urinary excretion of the polyamines putrescine, spermidine, and spermine. For comparative purposes, 9 normal 8-10 yr olds were similarly tested.
Subgroups 3 and 4 showed subnormal serum somatomedin C (average, 0.35 and 0.21 U⁄ml compared to 1.60 U⁄ml in the normals). They released normal amounts of nocturnal GH immunoreactivity, but the ratio of activities measured by RRA and RIA was subnormal (average of the ratios of the sums of the nocturnal RRA and RIA serum levels in subgroups 4 and 3 vs. normal, 0.22 and 0.38 vs. 0.98). Urinary excretion of the polyamines putrescine, spermidine, and spermine averaged 54%, 90%, and 53% of normal, respectively. In subgroups 1 and 2, average somatomedin C level, average nocturnal release of GH immunoreactivity, and average RRA to RIA ratios were all normal. In subgroup 1, urinary putrescine, spermidine, and spermine averaged 40%, 46%, and 25% of normal, respectively; in subgroup 2, these values were 64%, 104%, and 69%.
Our data suggest that in NVSS subgroups 3 and 4, the pituitary gland releases an endogenous GH with normal immunoreactivity but subnormal bioactivity. These subgroups can be readily recognized by their subnormal values for serum somatomedin C concentration and nocturnal serum radioreceptorassayable GH to radioimmunoassayable GH ratio. Urinary excretion of polyamines is depressed in most NVSS children and does not distinguish between the subgroups.
